In many offshore oil and gas applications, it is desirable to position machinery at or near the ocean floor. Designing complex industrial machinery to operate reliably and efficiently in underwater environments, however, presents significant challenges, such as protecting the machinery from the underwater environment. Further, these challenges can be complicated by a requirement that the machinery be designed to handle dirty or sour process gases, such as natural gas. A variety of designs have been proposed and implemented to overcome these challenges and protect the machinery from the subsea environment, while effectively operating with difficult process gases. As wellheads are pushed into deeper water, however, these challenges are compounded by higher hydrostatic pressure and an increased difficulty of reaching machinery disposed at location. For example, design steps are needed to minimize maintenance requirements as the components of the deepwater machinery may be difficult and costly to reach if a problem arises.
Some designs currently implemented use a compact, integrated motor/compressor, such as the DATUM® I, commercially-available from Dresser-Rand Co. of Olean, N.Y., USA. These current designs utilize ruggedized and/or corrosion-resistant construction suitable for marine environments and for handling difficult process gases. While such designs have been successful in a variety of applications, a need exists for a design solution that employs readily-available, efficient, and reliable machinery, which can be positioned subsea and can run with a minimal amount of support and maintenance from the surface.